Piston-ring.



.Plsou muc, APPLICATION FILED APR. I8. I9l6;

Patnte'd Oct 2, 1917..

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@l www UNTTED sTATEs PATENT OFFICE.

MILLARDL. DUNHAM, 0F NEW YORK, N. Y., ASSIGNOR OF ONE-FOURTH TO LOUIS DE F.

MUNGER, OF NEW YORK, N. Y.

PISTON-RIN G.

Specification of Letters Patent.

Patented Oct. 2, 1917.

Application led April 18, 1916. Serial No. 91,858.

To all whom 'it may concern:

Be it .known that I, MILLARD L. DUNHAM,

1a citizen of the United States and resident of the borough of Manhattan, in the city, county, and State of New York, have invented certain new and useful Improvements in Piston-Rings, of which the following is a specification.

This invention relates to piston rings, and consists in a certain method of treatment, or step in the manufacture of piston rings, whereby these devices are rendered more eliicient and serviceable in the performance of the functions for which they are designed.

Piston rings are usually made from cast iron, and rely for their outward tension, whereby gas tight relationship with the cylinder wall is provided, upon the inherent elasticity of the material from which cast, in the restoratory effort toward resumption of their original cont-our; after the inward compression to which they must be subjected. in order to introduce the rings, upon a piston, within the cylinder. Thus the rings are usually cast or otherwise produced of a diameter greater than the inside di- -ameter of the cylinder with which they are to be used, and are split at one point, by the removal of a portion of the ring material, leaving two opposed ends, to provide space for the aforesaid inward compression; the space being of such extent only that when abridgedl by the inward compression for service, the opposed ends will have spaced relationship just suli'cient to serve the purposes of heat expansion and contraction in use.

Under this ordinary method' 'of piston ring manufacture the true circular form becomes distorted when the ring is contracted to fit within the cylinder; the distortion consisting in portions of the ring, near its ends, lagging inwardly, leaving clearances between the outer peripheral surface of said portions-over certain arcs-and the opposed portions oflthe cylinder wall. These clearances permit sufficient leakage to affect the cylinder compression.

Various means have been sought to rectify this deficiency in piston rings. and my present invention is directedto a novel,

.simple and eiiicacious method, whereby a circular ring, produced in the ordinary way, is caused to have a true circular contour after it has been contracted to vfit within a cylinder.

This method, in brief, consists in first cutting a piece out. of a cast ring, in the usual manner; leaving opposed, separated ends; and then in spreading the mass of the ring material at'its outer peripheral surface, in portions thereof adjacent to each of its opposed ends; tol thereby give those portions, equally, an inherent, inward in clination; which constitutes, in the free state of the ring, a distortion thereof from a true circle; but which, inthe contracted state of the ring, for service, gives itvan absolutely true 'circular contour; whereby the clearances before referred to as existing between the ring portions. near its ends, and the cylinder wall, are entirely filled.

Spreading the mass of the ring material, in its portions toward the ring ends, has the effect of drawing the end portions of the ring inwardly, to give them equally a distorted contour, wherein ther ends aforesaid are inclined inwardly, and Said end portions caused to describe a segment of a. circle whose diameter is slighly less thanl the diameter of the untreatedportion of the ring in its free state. Y

This may be accomplished by punching indentations inthe outer peripheral surface of the ring, over longitudinal portions thereof including the ring ends and sections anterior thereto: the circumferential ring portions,` thus defined, comprising the arcs referred to in which leakage clearances exist under th'e present construction of ordinary y piston rings.

The mass spreading, as by punching of indentations aforesaid, has the effect of drawing inwardly the ring end portions, to thus slightly distort the ring in its free state; butv causing it to have a true cylintitl drical contour when contracted in service.

ltracted, assumes a p Other features and advantages of my said as stated, draws' inwardly the ring whereby the ring, when contrue cylindrical form.

crum, end portlons,

invention will hereinafter lappear. InV the drawing z-f "Figure'l is a'plan view of a circular ring from which a section has been removed to permit contraction.

2 is an edge view thereof, showing the method of forming indentations therein to spread the mass of the material.

Fig. 3 is a plan view, showing the effect of the'mass spreading 1n changing the ring ings of j larger diameter,

` the joint, will then sag inwardly,

' validly,

, of' the ring,

contour at one side of lthe spacing.

Fig. Ll is a similar view, showing the ring as treated in Fig.

3, to fit within a cylinder. Fig. 5 is an enlarged detail view, showing the ring as treated at both sides of the spacing and contracted to tit and Fig. 6 is an edge view of the ring' shown in Fig. 5.

In 'carrying out my improved method 'of producing pistonrings. from circular cast- I remove a section from a metal annulus, as 1,leaving the opapart sufficiently to allow the inherent elasticity" of` the ring material, when the ring is tted within'a cylinder, v.to exert the desired degree of outward tension.

'The fault inthis general form of ring construction, as now practised, is that. while the diameter of the ring, in a line drawn through remain practically unchan tracted, the sideportions o ed when conthe ring, near tracted, leaving at those points leakage spaces between defect is remedied by me by distorting the from its circular condition shown in Fig. 1, through a certain treatment which results in causing the ring ends 2, 3, and portions ,adjacent thereto, to 'incline inying the eli'ect, when the-ring is contracted;z tobring its ends together, of then causing ythe ring to assume a true cirular form. .l

" 2 illustrates the character of the treatapplied, as that of punching indentaas 4f; in the outer peripheral surface along restricted Aportions thereof lyingbetween the ringends and a medial line drawn across the ring, between its joint and heel.'y

Said indentations are produced by a tool, as 5, and serve to slightly spread the mass of the ring material at those portions, which tions,

within a cylinder, 1

its joint and heel, will the ring and cylinder.- Thisv 'the free end portions of said ring,

distortion in its free state, as stated, lwhich distortion enables the ring to assume an absolutely true circular form when contracted in service.

Reference to Fig. I3 will show one side only of the ring as treated, the treated side a,1n the free state of the ring being distorted, while the-opposite side 6 remains of .circular form. v In further illustration of the effect thus obtained, I have shown, in Fig. 4, the partly treated ring of Fig. 3 as contracted and placed within a cylinder 7 It will there be seen that the treated portion of the ring, as contracted, ts perfectly within the cylinder 7 the opposite, untreated side 5 of the ring appearing as distorted. in the contracted state,v whereby aclearance -is seen to exist between said portion 6 and-the cylinder wall. The eflicacy of this treatment, as applied to both portions 5a and 6 of the ring, is clearly shown in Fig. 5', where the ring is seen to fit closely tention is directed to'my co-pending application, Serial No. 91857, filed April 18, 1916, for piston rings, said ap lication referring to a piston ring capable oiiproduction under this application.

Variations may-be resorted tovwithin the spiritand scope of my claimed invention.

I'claim:

1. The method of producing leak-proof piston rings, consisting in removing a segment from a circular metal ring, and Inechanically compressing said rin'g'in its outer peripheral surface, at the end portions only thereof, thereby effecting a mass displacement in said outer surface, to draw inwhereby said ring,

2. The method of producing leak-proof piston rings, consisting in removing a segment from a circular metal ring, andpunching compressing depressions in its outer peripheral surface, at the end portions only thereof, thereby effecting a mass displacement in said outer surface, to draw inwardly whereby said ring, when contracted in service, is of truecircular form.

Signed at the borough of Manhattan in the city, county, and State of New Yorln this 14th day of April A. D. 1916'.

MILLARD L. DUNHAM.v

VVitneSSes: l i W. E. FEE,

F. W. BARKER.

within the cylinder. At-

vwardly4 the free end portions of said ring, when contracted for service, '1s of true circular form. 

